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Biomedical subjects

I B Tager

Publications and source records attributed to I B Tager.

At least 55 records · Page 3Linked to original sources
PubMed1995

Maternal smoking during pregnancy. Effects on lung function during the first 18 months of life.

The present investigation evaluated the effects of maternal smoking during pregnancy on the growth of lung function during the first 18 mo of life in 159 infants who were part of a longitudinal study of the effects of maternal smoking on respiratory health. Infant pulmonary function was assessed at 2 to 6 wk of age and at 4 to 6, 9 to 12, and 15 to 18 mo of age by partial expiratory flow-volume curves and helium dilution FRC. Maternal smoking was assessed by standard questionnaire and urine cotinine measurements. Maternal smoking during pregnancy was associated with a reduction of 9.4 +/- 4.3 ml (p = 0.029) for FRC and 33 +/- 12.3 ml/s (p = 0.008) reduction for flow at FRC (VFRC) after controlling for the effects of growth (length). The effect of maternal smoking was greater for female infants than for male infants. At 1 yr female infants exposed in utero were predicted to have a 16% reduction in VFRC compared with 5% for male infants. No sex difference was seen for FRC or VFRC/FRC. Exposure to environmental tobacco smoke in the postnatal period was not significantly related to reduced FRC or VFRC. These data provide further evidence that maternal smoking during pregnancy may play a greater role than postnatal and childhood exposure on the observed effects on lung function in children.

Female↗
PubMed1993

Trees and tracking.

Epidemiologists have used the term 'tracking' to connote an individual's maintenance of relative rank of some longitudinally measured characteristic over a given time span. To assess the extent to which an attribute tracks we have first to summarize individual growth curves, and second to quantify the notion of maintenance of relative rank, both in the face of random error. A sequence of papers appearing in 1981 provided differing methodologies for appraising tracking. Here we take a different approach to tracking by using regression trees for longitudinal data. The above two concerns are simultaneously addressed in that the procedure identifies subgroups, defined in terms of covariates, within which the collection of growth curves is homogeneous. After reviewing the existing approaches to tracking we describe the tree-structured methodology, and present an illustrative example pertaining to lung function growth in children.

Bias↗
PubMed1993

Lung function, pre- and post-natal smoke exposure, and wheezing in the first year of life.

The relationship between initial level of lung function and subsequent wheezing, lower respiratory illness (LRI) was studied in 97 infants in whom the first measurement of pulmonary function (PFT) was made before 6 months of age. Occurrence of LRI was evaluated by standardized questionnaires at each well-baby visit, biweekly telephone calls to mothers, and review of all visits to physicians. Infant PFT was assessed by partial expiratory flow-volume curves and helium-dilution measurement of functional residual capacity (FRC). Maternal, prenatal smoking was assessed by urine cotinine and standard questionnaires. Infants who developed an LRI during the first year of life had lower preillness length-corrected forced expiratory flow at FRC (VFRC) than those who did not experience an LRI (males, 2.06 +/- 0.20 versus 2.32 +/- 0.29 ml/s/cm; females, 2.38 +/- 0.20 versus 2.91 +/- 0.26 ml/s/cm). Similar results were observed with FRC-corrected VFRC. No differences were observed for FRC. Differences in lung function were greatest in female infants whose mothers did not smoke during pregnancy (VFRC 2.67 +/- 0.25 versus 3.49 +/- 0.26 ml/s/cm for those with and without LRI, respectively; p = 0.03). History of maternal wheezing was more common in infants who experience an LRI, independent of maternal smoking. The results were not influenced by exposure to nonmaternal sources of environmental tobacco smoke in the postnatal period. Regression analyses that included data for multiple measurements of VFRC over the first year and took account of duration of follow-up demonstrated that lower levels of VFRC were associated with an increased frequency of LRI, especially in female infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1993

Introduction to working group on tropospheric ozone, Health Effects Institute environmental epidemiology planning project.

The working group on tropospheric ozone of the Health Effects Institute has evaluated the need for epidemiologic studies on the health effects of ozone (O3) exposure. This paper summarizes current data and identifies possible research questions. The extent to which ozone exposure results in chronic health effects is largely undefined and is the central issue for epidemiologic studies. Most current data focus on transient endpoints; the link between acute changes in symptoms and/or lung function and possible chronic effects has not been established. Concepts of ozone-induced health effects have been extended to include processes of chronic disease (e.g., markers of ongoing inflammation and repair, markers of accelerated lung aging). Traditional epidemiologic studies performed have focused only on accelerated lung aging and are limited by a number of methodologic problems. Recent, very preliminary, studies suggest new opportunities for the use of human lung tissue and a variety biological response markers as part of epidemiologic studies. The identification of sensitive subpopulations with regard to ozone-induced health effects has been studied incompletely and is important both in terms of study efficiency and mechanistic insight. Methodologic advances in the reconstruction of past ozone exposure are seen as essential, as is the incorporation of emerging markers of biologic response to ozone into traditional epidemiologic study designs. Finally, more data on the joint and independent contribution of other ambient air pollutants to putative ozone-induced health effects is warranted.

Environmental Exposure↗
PubMed1993

Summary of papers and research recommendations of Working Group on Tropospheric Ozone, Health Effects Institute environmental epidemiology planning project.

This paper summarizes the themes and recommendations that emerge from the papers presented by the Working Group on Tropospheric Ozone. In terms of current knowledge, the following are considered of particular importance: a) lack of clear evidence for a human analogue of the terminal bronchiolar and proximal acinar changes observed in the lungs of ozone-exposed animals; b) lack of evidence for a connection between the acute respiratory effects of O3 and possible chronic respiratory effects; c) need to better define the characteristics of O3-susceptible individuals; d) the lack of adequate exposure assessment tools for reconstruction of lifetime O3 exposure; and e) incomplete information on the role of other ambient environmental pollutants in the facilitation of O3 effects or as a cause of effects attributed to O3 in human populations. Based on the above, several recommendations for epidemiologic research on health effects of O3 are offered. a) Studies to investigate the existence of chronic health effects of O3 are essential, particularly those that include autopsied human lung tissue and biologic and physiologic response markers. b) Studies are needed to link acute responses with chronic effects and should include joint epidemiologic and controlled-exposure assessments. c) Studies are needed to identify susceptible subgroups. Such studies should include newly emerging biologic markers of O3 exposure. d) Accurate and precise tools for chronic O3 exposure assessment need to be developed for use in retrospective and prospective studies. e) Collaborative studies between epidemiologists and laboratory investigators are needed to develop and evaluate markers of O3 exposure and to test O3 exposure models.

Animals↗
PubMed1992

The relationship of nasal disorders to lower respiratory tract symptoms and illness in a random sample of children.

We examined the relationship of nasal disorders, defined as frequent colds and sinus trouble, to lower respiratory tract symptoms in a random population of 718 children aged 4 to 11 years in East Boston, Massachusetts. Frequent colds were significantly associated with maternal smoking (odds ratio (OR) = 3.00; 95% confidence interval (CI) = 1.97, 4.58), and so was sinus trouble (OR = 4.73; 95% CI = 1.78, 12.51). After adjustment for maternal smoking, age and sex, frequent colds (OR = 2.88; 95% CI = 1.87, 4.42) and sinus trouble (OR = 4.95, 95% CI = 1.83, 13.39) remained significant predictors of lower respiratory tract symptoms in separate logistic regressions. If one restricted the cohort to the 513 children who also had personal smoking information and adjusted for this variable as well, the results for colds were unchanged (OR = 2.94; 95% CI = 1.78, 4.84) but the results for sinus trouble were now not statistically significant (OR = 2.30, 95% CI = 0.67, 7.94). We conclude that nasal disorders are associated with lower respiratory tract symptoms in children.

Child↗
PubMed1992

Effects of asthma on pulmonary function in children. A longitudinal population-based study.

Data from a longitudinal study of childhood factors influencing the development of chronic obstructive lung disease were used to assess the effects of asthma on lung function development in male and female children. A population-based cohort of 602 white children, initially aged 5 to 9 yr, was observed prospectively for 13 yr. Spirometry was performed and a standardized respiratory and illness questionnaire was administered by trained interviewers on a yearly basis. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and forced expiratory flow between 25 and 75% of vital capacity (FEF25-75) were used as measures of lung function. The total number of children reporting asthma over the course of the study was 67. Male asthmatic subjects (n = 42) had larger average percentage of predicted FVC than nonasthmatic males (n = 277). Female asthmatic subjects (n = 23) had a lower average percentage of predicted FEV1 than nonasthmatic females (n = 260). In a multivariate analysis of the individual lung function measures, adjusting for previous level of pulmonary function, age, height, change in height, and personal and maternal smoking, males reporting active asthma had a significantly larger FVC than males with no history of asthma. In contrast, females with active asthma had a significantly smaller FEV1 than females with no history of asthma. Both males and females with active asthma had decreased FEF25-75. From our analysis, we would predict that a female who develops asthma at age 7 would experience a 5% reduction in FEV1 by age 10 and a 7% deficit by age 15.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1992

The effect of maternal smoking during pregnancy on early infant lung function.

We studied the effect of prenatal maternal cigarette smoking on the pulmonary function (PF) of 80 healthy infants tested shortly after birth (mean, 4.2 +/- 1.9 wk). Mothers' prenatal smoking was measured by: (1) questionnaire reports at each prenatal visit of the number of cigarettes smoked per day, and (2) urine cotinine concentrations (corrected for creatinine) obtained at each visit. Infant PF was assessed by partial expiratory flow-volume curves and helium-dilution measurement of FRC. Forced expiratory flow rates were significantly lower in infants born to smoking mothers, both when unadjusted and after controlling for infant size, age, sex, and passive exposure to environmental tobacco smoke (ETS) between birth and the time of PF testing. Flow at functional residual capacity (VFRC) in infants born to smoking mothers was lower than that found in infants whose mothers did not smoke during pregnancy (74.3 +/- 15.9 versus 150.4 +/- 8.9 ml/s; p = 0.0007). Differences remained significant when flow was corrected for lung size (VFRC/FRC: 0.87 +/- 0.26 versus 1.77 +/- 0.12 s-1; p = 0.013). No differences in pulmonary function were evident among infants exposed and unexposed to ETS in the home after stratifying by prenatal exposure status. We conclude that maternal smoking during pregnancy is associated with significant reductions in forced expiratory flow rates in young infants. The results suggest that maternal smoking during pregnancy may impair in utero airway development and/or alter lung elastic properties. We speculate that these effects of maternal prenatal smoking on early levels of forced expiratory flow may be an important factor predisposing infants to the occurrence of wheezing illness later in childhood.

Adult↗
PubMed1992

The effect of smoke inhalation on lung function and airway responsiveness in wildland fire fighters.

The current study was undertaken to evaluate the effect of smoke on forced expiratory volumes and airway responsiveness in wildland fire fighters during a season of active fire fighting. Sixty-three seasonal and full-time wildland fire fighters from five U.S. Department of Agriculture Forest Service (USDAFS) Hotshot crews in Northern California and Montana completed questionnaires, spirometry, and methacholine challenge testing before and after an active season of fire fighting in 1989. There were significant mean individual declines of 0.09, 0.15, and 0.44 L/s in postseason values of FVC, FEV1, and FEF25-75, respectively, compared with preseason values. There were no consistent significant relationships between mean individual declines of the spirometric parameters and the covariates: sex, smoking history, history of asthma or allergies, years as a fire fighter, upper/lower respiratory symptoms, or membership in a particular Hotshot crew. There was a statistically significant increase in airway responsiveness when comparing preseason methacholine dose-response slopes (DRS) with postseason dose-response slopes (p = 0.02). The increase in airway responsiveness appeared to be greatest in fire fighters with a history of lower respiratory symptoms or asthma, but it was not related to smoking history. These data suggest that wildland fire fighting is associated with decreases in lung function and increases in airway responsiveness independent of a history of cigarette smoking. Our findings are consistent with the results of previous studies of municipal fire fighters.

Adult↗
PubMed1992

Atopy and airways reactivity in animal health technicians. A pilot study.

Smoking, response to allergen skin testing, and nonspecific airways reactivity in students entering a career program for animal health technicians (AHT) were studied at their entrance and 7 months into the program to determine whether such persons provide a suitable cohort to overcome the selection biases accompanying investigations of occupational asthma. Previous occupational exposure to animals (65%) was associated positively with allergic symptoms but negatively with skin response to animal allergens and to airway hyperreactivity (AR). AHTs remaining in the program were more likely than those dropping out to have (1) worked with animals, (2) positive skin responsiveness to animal allergens, and (3) AR; the latter was significantly associated with positive skin-test responses to animal allergen testing. This study demonstrates that significant exposure to animals may have occurred among workers entering animal-handling careers. Additionally, competing "healthy" and "resistant" worker effects operate among AHTs to influence the prevalence of occupational asthma in this population.

Adult↗
PubMed1991

Temporal trends in chronic obstructive lung disease case fatality in hospitalized US veterans: 1970-1987.

Vital statistics data have suggested that age-adjusted mortality from chronic obstructive lung diseases (CLD) is increasing. The present investigation has used the US Veterans Administration (VA) hospital computer database to determine whether trends in CLD case fatality follow trends in CLD population mortality. Data for male patients discharged from 172 VA hospitals from 1970 through 1987 were utilized. Patients were included if they had a CLD as a first-listed hospital discharge diagnosis, did not have any of a number of smoking-related cardiovascular or malignant diseases, and were born in the years 1900 through 1939. While crude case fatality for all CLD increased from 5.2 percent in 1970 to 7.4 percent in 1987, age-adjusted case fatality decreased from a peak of 8.5 percent in 1971 to 5.8 percent (95 percent confidence interval, 5.4 to 6.61 percent) in 1987. This trend was seen for all CLD diagnoses, including asthma. Age-specific case fatality decreased for each successive 5-year birth cohort, and age at death remained relatively constant over the last 14 years of the study. The declining case fatality could not be explained by changes in the ICD coding rubrics. The extent to which case fatality has been declining due to improved treatment and/or cohort-related changes in tobacco smoke exposure could not be determined definitively from the data.

Age Factors↗
PubMed1990

Early childhood predictors of asthma.

To investigate potential risk factors for the development of childhood asthma, the authors undertook a longitudinal study using a cohort of 770 children aged 5-9 years from East Boston, Massachusetts, that has been under study since 1975. The disease outcome considered was age at first onset of asthma, as determined by parental or self-reporting of a physician's diagnosis. Potential risk factors were evaluated specifically in relation to their presence antecedent to a diagnosis of asthma. Standardized questionnaires were used to obtain childhood illness histories, environmental exposures, and the asthmatic and atopic statuses of first-degree relatives. Ninety-one cases of asthma were identified from 1975 to 1988 (57 males and 34 females). Significant sex-adjusted relative risk estimates were seen for antecedent pneumonia, bronchitis, hay fever, sinusitis, parental asthma, and parental atopy. Neither bronchiolitis, eczema, croup, personal cigarette smoking, maternal smoking, paternal smoking, nor delivery complications bore an apparent relation to the development of asthma. A history of parental asthma or parental atopy did not significantly alter the sex-adjusted relative risk estimates for pneumonia, bronchitis, hay fever, or sinusitis. These results support the hypothesis that asthma is a multifactor disease whose expression is dependent on both familial and environmental influences.

Asthma↗
PubMed1990

Pulmonary function measures in healthy infants. Variability and size correction.

We conducted 151 tests of pulmonary function (PF) on 72 healthy infants younger than 2 yr of age using partial expiratory flow volume (PEFV) maneuvers and helium dilution determination of FRC. After tests were grouped into four strata based on postconception (PC) age, variability and sex differences in level of PF were examined. No significant sex differences were found for any PF measure in any age stratum, even when somatic size was controlled by length correction. Force expiratory flow measures, however, tended to be greater in girls than in boys in the youngest infants. Flow measures demonstrated greater between-subject variability than did volumes, and variability was greatest in the youngest infants. Within-subject variability also was more pronounced for flow measures, particularly in infants younger than 50 PC wk of age. Across the age range of infants studied, all PF measures were related linearly to somatic size as measured by either length, weight, or chest circumference. Length offered the best individual size correction of the three size parameters studied. Linear regression of PF parameters versus length demonstrated FRC to increase at 5.39 ml/cm over this age range, whereas flow at FRC increased by 9.67 ml/s/cm. We conclude that the variability of infant PF measures is greatest in early infancy, that measures of forced expiratory flow are more variable than volume measures, and that sex differences in infant PF do not appear significant. Length is related linearly to PF measures and offers reasonable size correction for healthy infants younger than 18 months of age.

Age Factors↗
PubMed1989

Familial factors related to lung function in children aged 6-10 years. Results from the PAARC epidemiologic study.

Familial factors related to lung function between six and 10 years of age have been studied among 1,160 children whose both parents were examined in 1975 in the French PAARC (Pollution Atmosphérique et Affections Respiratoires Chroniques) Cooperative Study. The three indices FVC (forced vital capacity), FEV1 (forced expiratory volume in one second), and FEF25-75 (forced expiratory flow between 25 and 75 per cent of the vital capacity) were studied after adjustment for sex, town, age, and height (and weight for children's FVC and FEV1). Maternal (but not paternal) smoking was associated with a significant decrease in FEV1 and FEF25-75, but not in FVC. Familial resemblance was observed for all indices between children and parents and between siblings. None of the environmental factors considered (i.e., parental smoking or education) or body habitus explained the familial resemblance observed. Conversely, after taking into account the aggregation between siblings, associations between children's lung function and parental characteristics (smoking, lung function) remained significant. Parental-children correlations exhibited an increasing temporal trend with increasing age of the children. All but one correlation for FVC, FEV1, and FEF25-75 residuals of children with mothers' residuals were higher in the oldest age group compared with the youngest age group at the 0.10 level. Furthermore, correlations between siblings of opposite sex were significantly lower than correlations between siblings of like sex, especially for FEV1/FVC and FEF25-75/FVC. Results suggest that different growth patterns between boys and girls may be a critical factor in the study of lung function familial resemblance.

Age Factors↗
PubMed1989

Comparison of questionnaire and diary methods in acute childhood respiratory illness surveillance.

We compared two prospective survey methods, an interviewer-administered questionnaire and a daily diary, used concurrently to record acute respiratory illness experience over a 2-yr period in 422 children 5 to 11 yr of age from East Boston, Massachusetts. Respondents contributed more months of data with the questionnaire than with the diary method. Respiratory symptom and illness rates, as determined for the first year by each of the methods, were compared for 277 children who had less than 4 months of missing data. Respondents from families with more children tended to report a lower total respiratory illness rate by the diary than by the questionnaire method (p = 0.006). Although upper respiratory illness rates did not differ by method, lower respiratory illnesses were reported more frequently (p = 0.0001) by questionnaire than by diary. In the group of 49 children who were identified as having had greater than one lower respiratory illness, 25% of the illnesses reported as having been lower respiratory by questionnaire were reported as having been another form of respiratory illness by diary. For this group the ratio of 3:1 of boys to girls for the diary as compared with 1.5:1 for the questionnaire suggests the presence of reporting bias and no comparability of methods. Standardization of an acute respiratory illness questionnaire would provide greater opportunity than use of diaries for synthesis of prospective data from different epidemiologic studies.

Acute Disease↗
PubMed1989

Longitudinal variability in airway responsiveness in a population-based sample of children and young adults. Intrinsic and extrinsic contributing factors.

The degree and long-term variability of airway responsiveness to eucapneic hyperventilation with cold air was assessed in 287 children and young adults (less than 23 yr of age) (735 challenge tests) enrolled in a longitudinal study of pulmonary function, 179 of whom underwent two to five cold-air challenge tests between 1982 and 1986. Survey-to-survey variability in airway responsiveness was assessed with computation of adjusted within-subject correlation coefficients for continuous measures of response (percent decrease in FEV1 after challenge) and with adjusted odds ratios for dichotomous outcomes ("positive" if percent decrease FEV1 greater than or equal to 0.13). The relationships between variability in responsiveness and the following variables were examined: age, baseline level of pulmonary function, presence of respiratory symptoms and illnesses, smoking exposures, season, level of ventilation achieved during testing, and temperature of the expired air. Airway hyperresponsiveness was demonstrated consistently over all surveys in only six of 49 (12%) subjects who had ever demonstrated a "positive" airway response. The odds relating positive responses between surveys was 12.1 for airway hyperresponsiveness, 21.5 for "persistent" wheeze, and 6.7 for "any" wheeze. Significant predictors of airway hyperresponsiveness were wheeze symptoms (OR = 2.3), hay fever (OR = 1.6), and a chest illness requiring bed rest (OR = 2.5). Adjustment for survey-to-survey differences in respiratory symptoms, or for differences in testing conditions between surveys, did not alter the observed variability in airway responsiveness. Adjustment for "random error" (assessed with replicate measures of airway responsiveness in a subsample of 21 subjects) improved the observed survey-to-survey variability by 30%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

The relationship between longitudinal change in pulmonary function and nonspecific airway responsiveness in children and young adults.

The relationship between airway hyperresponsiveness and longitudinal change in lung function was assessed in a population-based sample of 184 children and young adults observed over a maximum span of 12 yr. Pulmonary function was assessed annually with spirometry, and health and household information was obtained with standardized questionnaires. Nonspecific airway responsiveness to eucapneic hyperventilation with subfreezing air was measured on at least two occasions between the sixth and twelfth annual surveys. At any given survey, a significant bronchoconstrictor response was defined as [( prechallenge FEV1-postchallenge FEV1]/pre-FEV1) greater than or equal to 0.13, a value that identified 10% of the population. Subjects were classified as "never", "always", or "inconsistent" responders according to the consistency of responsiveness determined in different surveys. Subjects were classified further as "labile" if their maximal survey-to-survey difference in delta FEV1/FEV1 was greater than or equal to 0.18, and as "nonlabile" otherwise. A Markov-type autoregressive model that adjusts for previous pulmonary function level, sex, growth variables, and smoking exposures was used to model growth of FEV1, FEF25-75, and FVC. Overall, 135 (73%) of subjects never responded to the cold air challenge, six (3%) always responded, and 43 (24%) responded on one but not all occasions. Levels and rates of increase in level of FEF25-75 were significantly lower in the inconsistent and always responders. In contrast, levels of FVC were greatest and increased most in the always responders. In labile subjects, both FEF25-75 and FEV1 growth rates were reduced. These effects persisted when asthmatics were excluded from the analyses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗